Security is a fundamental requirement for networks of the like, or of any kind managing sensitive data, to ensure the secure information exchanged between the different nodes of the network, and also to control access to the network devices by other users, external to the network.
Accordingly, these networks require a security system taking into account several main issues:                a trust issue, for providing means to the different nodes of a network for identifying, authenticating and trusting any other node as being a member of the same network,        a secure communication issue, for providing means to enable secure communications between the different nodes of the network, and        an access control issue, for providing a mechanism of restricted access to information or nodes of the network.        
Conventional methods for operating such networks generally provide a master node, being a personal manager device or a trust center, used for pre-distributing cryptographic material to the nodes of the network, and then for authenticating each node as belonging to the network, when communications have to be established between the nodes. However, these methods have several drawbacks:                first of all, these methods do not allow two nodes of the network to authenticate each other without referring to the master node, and        in addition, since the cryptographic material is pre-distributed to the nodes of the network, it does not allow providing access to an external user of the network.        
Besides, methods based on public-key cryptography have been proposed for granting access to external users of a network in a trustful and secure way. However, these methods are not resource-friendly from the computational point of view and require the transmission of long keys. Thus, these methods require communication, computation and memory capacities that are not always available in devices used in personal area networks, which are generally resource-constrained.